Two-thirds (68%) of people questioned who have paid a charge for a financial service or product in the last year agreed that companies make costs more complicated to cause confusion and only one in five (19%) think charges are representative of firms' actual costs.
The consumer group Which? is urging the Government and the regulator to conduct a review of all financial fees and charges, including those on insurance policies, mortgages, bank accounts and credit cards, "to make sure the price you see is always the price you pay".
It says showing fees and charges upfront will allow people to shop around more easily and compare overall costs.
More than 2,000 people were surveyed, of which just under half had paid a fee or a charge on one of these financial products in the last year.
Six in 10 (62%) agreed it was difficult to compare the total cost of financial products and services as fees and charges vary so much.
A separate Which? investigation into the car insurance market found that despite premiums being generally on a downward path, fees have been increasing.
Of 28 car insurance firms looked at, some had doubled or even, in one case, tripled their cancellation charges since similar research was carried out three years ago.
The Association of British Insurers said insurers, intermediaries and price comparison websites were required by the Financial Conduct Authority to clearly set out to the customer before and after the contract was agreed, in addition to the premium, other charges that could arise, such as administration costs for policy alterations and cancellation charges.